Oxidation of aromatic hydrocarbons



Patented Dec. 29, 1953 864,447 OXIDATlON-BFQERUMATICHYDROCARBONS 7 "Eugene li fllosranzl, wilmingtiiffieh; a" ti Winn- E.

Reese.- S

"c'iiles "Powder C corporation of De'l'aware 2N0 Drawing. ap lication has "5, "1 94s, serial No. 31394 Prior to the zproce'ss of this invention-weeni dation of compounds such as cli isopi'oipylbenzene was found to lead to the-formationnf products containing considerable amounts -'.of ketones alcohols. In the oxidation :of:ipediisopropylhen zene, :for example the voxidation led primarilyato the formation of p-isopropyl aacetop'henonefan'd a,a-dimethyl-p-isopropy1leenzyl alcohol. There was no successful process for effecting the preparation of substantial ,yields of a,a-dimethyl-pisopropylbenzl hydroperoxide or of a,a,a,a-tetra- .methyl-p-xylylene olihydreperoxide from ;,p=di= .isopropylbenzene.

Now in accordance with this invention ithas been found that the preparation :of tertiary ny: droperoxicles from alkyl suhstituted aromatio organic compounds having "the above structural formula may be carried outby passing ah oxygen oontainin'g gas through saidcompounds .in the liquid phase at moderatelyi'elevatedtemperatures in the presence of low concentrations of :a datalytically active heavy metal compound.

In carrying out .thefp'rooess of this invention manganese naphthenate, for example, is iiis solved in p di'isopropylb'enzene and :the latter then is agitated vigorously while a stream :of

air "or oxygen is simultaneously blown through the :reaction :mixture. The reaction "is carried out'at a temperature betweehabout 40andiabout 70 C. until standard analytical idataisuch asre fractive index indicate the conver'sionofiapproxi mat-ely so to 70% ?f the lp-idiisopropylbhhzen.

Utilizing known techniques the "reaction mixture then may be worked up to recover a reaction product containing preponder'ant amounts :of -u,a dimethyl-peisopropylbenzyl :hydroperoiii'de. At the higherlevelsof conversionito hydroperok- .ide the reaction produ'ctla'lso will contain aicon :siderable amount of a,cm' ul' tetiarnethylep .xylylene dihydfoperoxirie which crystallizes easily from the reaction mixture.

The following examples-constitute specific il- Q "lustiations offthefprocess of"this invention; an amounts are based "6'11 tans by weight.

Five hundred parts i of i commercial diisopropyl *benzehe "(refractive index at C.-, 1548538) which parts of 'rnanganes'e neiphtheriate of 6% manganese content 'had be'en dissolv'ed was placed in a closed l'e'a'ct'ion ves'se1 equipped :witn a re flux-condenser, a enema-ruse openin through a porous 'iritted gl'ass plate-, a thermometer, an "efficient hig'hsp an agitator. reaction vessel was immersed in a constant tempetature bath inaintained a5 Through the -inie't p'ei- 'hbu'lf per "kilogram diistpropyibenzi ne. The reaction rated ty the autumn-1dr as v' io'u-s i'-un-, this oiiikliZi-Sd aiisoe'ropyibe'rizeae c'o L *taini-ngtm)% a,a-tlirrrethy opropyl-ben droperoxide. Samples we r-iodic intervals for refractive ;index and hydroperoxide determinations, the hydroperozgide content of the noting the amount benzene to oxidized ina tria'l's. at the'en r 43 hours the refractive inpresrwas 115005 "(approi'ii inately 58% conversion) and the amount bi taeingetn ianscpnpnmsfin htuieperende was 34.6%. m

'Ei'zirz'pl 2 The process 'of'Example l was-duplicatedwith the exception that the reaction was :run :for a much longer length -of time and "the temperature was raised to (3; at the-end of 7 5 hours.

At the end of 24 :hours the refractive index of.

the oily reaction mixture was 1.4972, this injdteating a conversion of about 40%; and the ghy dro peroxide content was {26:970. At the-end of ill hours thehvdroperoigide content was 293%. At the end of 48 hours the refractive index was 1 .4986 and the 'hydroperoxide' content was 3 148% Upon completion of 49 hours=of -oxidation an ad= olitional 1 25 :parts of manganese naphthenate was'added to the reaction mixture. At the end of -hours the hydroperoxide' content was 32:693. Upon completion of 74 hours ef-oxidation the refractive index was *l;5002, this indicating weenversion of about 55%; and the hydroperoxili content was 36:475. The temprature was 3 raised to 50 C. upon completion of 75 hours of oxidation and the reaction continued at this temperature for an additional 24 hours. At this time the refractive index of the oily reaction mixture was 1.5012, this corresponding to a conversion of about 60%, and the amount of (1,0. dimethyl-pisopropylbenzyl hydroperoxide was 39.2%.

Example 3 One hundred thirty-eight parts of p-ethylisopropylbenzene (refractive index at 20 (3., 1.4932; boiling point at 6'7 mm./sq. cm. pressure, 115.4 115.8 C.) in which 0.7 part of manganese naphthenate of 6% manganese content had been dissolved was charged into a closed reaction vessel equipped with a reflux condenser, a gas inlet tube opening through a porous fritted-glass plate, a thermometer, and an efficient high-speed agitator. The reaction mixture was heated to 50 C. Through the inlet tube oxygen was introduced at a rate of 10 liters per hour per kilogram of pethylisopropylbenzene. The reaction was initiated by the addition of 7.16 parts of oxidized cumene, this oxidized cumene containing 58.2% a,a-dimethylbenzyl hydroperoxide. The color of the reaction mixture turned deep brown and an exothermic reaction took place. Heating was stopped and the reaction mixture cooled to remove the excess reaction heat. At the end of 18 hours the color of the reaction mixture turned to light amber, the refractive index was 1.4995, and the hydroperoxide content 10.2%. An additional amount of manganese naphthenate (0.? part) then was added to the reaction mixture and the oxidation continued for an additional 48 hours, the temperature being maintained between 50 and 60 C. At the end of this time the reaction mixture had a refractive index of 1.5028 and contained 18.8% a,a-dimethyl-pethylbenzyl hydroperoxide.

Example 4 Five thousand parts of commercial diisopropylbenzene (refractive index at 20 0., 1.4899) in which 15.6 parts of lead naphthenate of 32% lead content had been dissolved was placed in a nickel autoclave equipped with a reflux condenser, a stirrer (200 R. P. M.) and designed for high-pressure oxidations. The autoclave also was charged with 207 parts of oxidized cumene to initiate the reaction, this oxidized cumene containing 72.2% a,a-dimethylbenzyl hydroperoxide. Oxygen was passed through the reaction mixture at a rate of 0.0276 cubic feet per minute per kilogram of diisopropylbenzene for four hours. During the oxidation the temperature within the autoclave was maintained at 120 C. and the pressure at 60 pounds per square inch. Upon completion of the oxidation there was obtained 5440 parts of crude reaction product. The refractive index of the crude product was 1.4961, this indicating a conversion of 32.6% of the diisopropylbenzene to oxidized materials. Analyof 23.3% a,a-dimethyl-p-isopropylbenzyl hydroperoxide.

sis of the reaction product showed the presence oxidized in accordance with this invention is the presence of a tertiary carbon atom carrying a hydrogen atom as its fourth substituent. As shown by the structural formula the carbon atom is tertiary because it is directly connected to three other carbon atoms contained in the groups represented by R1, R2 and Ar. The alkaryl group need not be derived from benzene as is the case in diisopropylbenzene. Compounds containing aromatic nuclei such as those derived from naphthalene, anthracene and phenanthrene also are operable, but some of these compounds, being solids, must be dissolved in a suitable solvent, such as benzene, during the liquid phase oxidation. The alkaryl group essentially is an aromatic nucleus substituted with one or more alkyl groups containing two or more carbon atoms. Representative alkyl groups composing the alkyl side chain portion of the alkaryl group may be illustrated by the ethyl'group in p-ethylisopropylbenzene, the isopropyl group in p-diisopropylbenzene and the two isopropyl groups in triisopropylbenzene and the groups may, for example, be ethyl, propyl, isopropyl, butyl, isobutyl, secondary butyl, tertiary butyl, and the like. Those compounds containing alkaryl groups in which the alkyl substituent contains, directly attached to the aromatic nucleus, a tertiary carbon atom carrying a hydrogen atom as its fourth substituent, are capable of being oxidized to dihydroperoxides. Illustrative of such compounds is diisopropylbenzene, which may be oxidized to ,a-tetramethyl-p-xylylene dihydroperoxide. Similarly, compounds containing two tertiary alkyl substituents in the alkaryl group may be oxidized to trihydroperoxides. Exemplary of such compounds is triisopropylbenzene. The alkyl substituents in the alkaryl groups may, in other words, have the same configuration as the tertiary alkyl group in the structural formula shown previously. The alkyl groups as represented by R1 and R2 in the structural formula need not be limited to the methyl groups of p-ethylisopropylbenzene and diisopropylbenzene. Other alkyl groups such as those previously indicated as suitable in composing the alkyl substituents of the alkaryl groups may be utilized, and R1 and R2 may be either the same or different.

The examples have set forth the use of molecular oxygen as the oxygen-containing gas but air also may be used. The oxygen may be furnished also in mixtures of oxygen with nitrogen or other inert gases. Oxygen, when used alone, may be in the form of pure or commercial oxygen. Air may be utilized either as it is readily available or as humidified up to the saturation point. Furthermore, it is advisable to wash the air with a caustic solution in order to remove carbon dioxide. The rate of input of the oxygen-containing gas may vary within a wide range, depending upon the concentration of oxygen in the gas, the activity of the catalyst, the pressure at which the oxidation is carried out, and the efficiency of dispersion. In general, at atmospheric pressure the rate of input will vary from about one liter to about liters per hour per kilogram of the alkyl-substituted aromatic organic compound, a preferable range on this basis being from about 5 to about 25 liters per hour per kilogram. At superatmospheric pressures, for example, 50 to 200 mounds rperzisquareeinch', the :ra'te :"of input may be from; aboutdimtozabout szio liters per hour :per :kilogram aof :tthe ialkaryl .compound, a prefera'ble range being "from about .150 'ito about 280 liters {per hour per :kilogram.

The oxidation .process :of this invention #is cart riedcout ineth'e presence iof :a"catalytically active heavy metal compound, particularly of such .imetalsw as manganese, cobalt, .lead, iron, nickel,

icopper, ivanadiumgchromium -'an'd" mercuijy. The

a oxides, hydroxides, :or :iorganic acid salts :of' any of :these :metals or icombina'tions thereof :which are soluble inithe alkylesubstituted aromatic 'oraganic (compound. or solutio'n Ithereo'f in'a suitable solvent may be employed. wIheiheavy metal salts :of :organic :acids are :particularly useful as catalysts in accordance with this invention. Exemiplary :of such salts :are manganese-buty l phthaleat-e, gmanganese linoleate, manganese .naphthcin .iate, admixture of :manganese and lead acetates,

=-cobalt linoleata cobalt,naphthenate, mixed leadcobalt naphthenatc, and :the heavy :metallresinates, such as manganese, lead or cobalt resinate. The resinates may be derived from any rosin acid, such as abietic, 'pimaric, dehydroabietic:

dihydroabietic or tetrahydroabietic acid. Those oxidized oils obtained according to the process of this inventionland containing preponderant amounts oilhydroperoxides are useful in initiate ing.the oxidation reaction by relieving inhibitions ,caused by harmful impurities. These oxidized oils, however, .do not act asactual catalysts and are thereforeh'ighly desirable initiators for those oxidations which ,exhibit inhibition.

"The concentration of the catalytically active heavy metal compound is critical in obtaining hig'hhydroperoxide yields. -If the concentration -..of the catalyst .is .too low, the reaction is too lslow and if the catalyst concentration is higher than the-maximum value utilized in accordance with this invention, the yieldofhydroperoxide will be adversely affected. In generaLhigh hydroperoxide yields maybe obtained if'the concentration of the catalyst in solution in the oxidation reaction mixture is at any particular instant from about 0.15 to about 0.8% based on the alkylsubstituted aromatic organic compound. A pref- "erable range on this'basisis fromabout i-2 to --about"-0;6 and a particularly applicable range is from'about 025to-about 0.5%. *Since many ofthe heavy metals have a tendency to precipitate as peroxides, such as manganese dioxide,

"activity -of' the catalyst. "It is possible, for example, in the preparation of the heavy metal salts of organic acids to vary the amount of metal contained in the final salt, consequently smaller amounts of a salt containing a relatively high metal content will 'be needed in comparison to ithe :same fsaltscontaininga smaller amount of -;-.the:meta1. :Eiimilarly the :cobalt salts are more 'iactive than the manganese andlead salts, and athesnaphthenates are more active than the lineleates, which in turn are more :active than the :"acetates. *Eonse uently, asmaller amount of co-, 'bailtinaphthalene, for example, willbeneeded than will be needed in the case .ofleadnaphthenate or manganese llinoleate. Relative to the hydrospemxidesrich ,0115 which ay b used to initiate -the soxidation reaction, ,these -011-S ma-y -b used s in ;:amounts --varying .0111 about 11 iito rabout $092, based on the alkyl-substitutedzaromaticzorganic compound but :a :preferabletrange sis :from :about i2 ito about 20%.

The temperatures: at 4 whichzthe .oxidations flare carried out also are :Iquite :criticalrin :obtain ing optimum yields of .ihydroperoxides. Illhe itemgperatures which :actua'llyemay ".besused, however,

will depend on athe v:pressune :existing during the oxidations. Upon the :basisofiatmosphericzpresv:sure, :the. temperature zshould :bezinzthe range of about 40 tovaboutfm" lC iai-moredesirziblerrange being between about 45":and abouti" C.,: and:a :particularly advantageous mange being .between about 150 .zandsabout 60:C. :The minimum :tem-

;perature of 2405C..1i$ necessary since :the'aprocess of this 1nventicn-:u.tilizes lowscatalystpconcentrations and .the grate of areaction cat, for example, room gtemperaturazis too slowjto bezof commercial sign ficance. -(Dn@the;other -hand, if :the tempera- ;ture during oxidation .is ..too .high, the .a-reaction oceursinsuchga mannerzasitoresult in excessive ketone formation. .e-lEn the base-10f pediisopropylbenzene, for ,exampla toxiidation;athigh temneratu1es at atmospheric pressure will zresultdn athe Temperatures greaterlthan'm ,C; may be :used, however, in the process ;of this :invention;-,provid- ,ing the pressure is increased to ,greater than atmospheric. although elevationof the .;temperature during the oxidation to, greater than Z0 C.

will cause increaseddecomposition of .the hydroperoxides to ,ketones, ?this..,is 'offset by .the in creased rate iof-hydroperoxide 'formationscaused by the elevation of :the pressure. .Also it is possible to hinder :the decomposition :of ithe-hydroperoxides to -ketones, aslcaused by elevation .of the temperature, by rusing a .low activity lcatalyst such as lead naphthena-te or linoleate, and by maintaining the catalyst concentration at alow level within' therbroad -ran ge.-of -.0.l-5 to 0.8%. A catalyst concentration between about 0.15 and .1about-0.3% generally .is satisfactory. :In other words, by proper-selection of pressure, catalyst and catalyst concentration, temperatures above C. may be used duringithe oxidationto obtain in shorter lengths of time oxidation reaction products having hydroperoxide-andhetone .contents as desirable as those reaction products-obtained at a temperature- .01 370 -.C. or less. The

' amount of ketone willnot be outof proportion to the amountof hydroperoX-ide. Usingpressures greater than atmospheric the process of this invention thereforemay be carriedout at temperatures between about .40" andabout 140C a more desirable range being between about :45 and about 130 (1., and :aparticularly advantageous range being between-about 5.0(and about C.

The pressures "-.WhiCh can be utilized l .during those .ox-idations carried out at greater than atmospheric pressure are ;-limited only by equipment design. .From a practical standpoint pressures from atmospheric HD4130 about 500 pounds per square inch are feasible. Apreferablerange is fromabout 50 -.to. about .200 pounds ,per square inch.

Since the reaction is heterogeneous, suitable agitationis necessary. :It is particularly important to bring the air, oxygen, :orother oxygencontaining gas into intimate :contact with "the liquid phase, and this-may be -.effected by using high-speed stirrers, suitable nozzles, porous plates or their combinations.

The course of the reaction may be followed by taking samples at intervals and determining the refractive index of the oily material. In the oxidation of diisopropylbenzene, for example, refractive index values between about 1.4955 and about 1.5030 indicate that about 30 to about 70% of the original organic material has been oxidized, and the reaction then is advisably interrupted. Conversions from about 30 to about 70% can easily be obtained in the process of this invention and it is desirable in obtaining high hydroperoxide yields to carry the conversion up to about 50-70%, since it generally is not until this conversion value is exceeded that undue amounts of secondary products such as the corresponding alcohol or ketone are formed.

The method utilized in recovery of the reaction products will vary depending upon the use to which the hydroperoxide is to be put. Ii the use of the hydroperoxide does not require separation of the hydroperoxide from other components, such as alcohols, ketones and unreacted starting material which may be present in the crude reaction mixture, the oily reaction product may be filtered through a layer of some filter aid to remove the catalyst by adsorption, then washed with dilute aqueous alkali and used either in the wet, slightly cloudy state for various purposes or after clarification and drying by filtration. The dilute aqueous alkali used in the washing step may be sodium hydroxide, sodium carbonate, sodium bicarbonate, and the like, the concentration of these alkalies in aqueous solution ranging from about 1 to about 10%, but preferably from about 2 to about 5%. If it is desired, however, to obtain a highly concentrated hydroperoxide, the crude reaction product, after the alkali wash, may be stripped of unreacted hydrocarbon by distillation at pressures of about 1 to about millimeters of mercury per square centimeter. The hydroperoxides themselves may be safely distilled at temperatures below about 100 0., this requiring the use, however, of pressures of about 0.01 to about 1.0 millimeter. Another method of separating the hydroperoxides from the crude oily reaction product involves precipitation of the hydroperoxide with a concentrated aqueous solution (25 to 40%) of sodium hydroxide. The precipitate is crystalline and on the basis of analysis is a compound of the hydroperoxide with sodium hydroxide and water.

The oxidation according to this invention ap parently proceeds by a peroxide mechanism. Using p-diisopropylbenzene as an example, when this compound is oxidized with molecular oxygen, a hydroperoxide is formed on the tertiary carbon atom of one of the isopropyl groups. In the presence of the small amount of catalyst utilized in accordance with this invention, a very small fraction of the hydroperoxide is decomposed, resulting in the formation of free radicals which are sufiicient to initiate the formation of more hydroperoxide molecules. If the concentration of the catalyst exceeds the amount specified in accordance with this invention, increasing amounts of hydroperoxide will decompose, resulting in an acceleration of the over-all oxidation,but decreasing the amount of undecomposed hydroperoxide at the expense of the formation of secondary products such as alcohols and ketones. That the oxidation follows a chain mechanism is shown by the existence of an induction period, by cases of inhibition, and by the fact that both may be eliminated by the addition orhydroperoxiderich oils from a previous oxidation run.

The process of this invention is advantageous in that it has been found possible by proper selection of catalyst concentration and temperature to obtain aryl(dialkyl) methyl hydroperoxides. These hydroperoxides are highly useful and find various commercial applications. They are excellent catalysts for the polymerization of vinyl, vinylidene, and vinylene compounds, being, for example, highly useful in the copolymerization of butadiene and styrene to form synthetic rubber, and they also are useful in rubber reclaiming, in flotation, and in kier boiling, bleaching and other textile operations.

What we claim and desire to protect by Letters Patent is:

1. The process of preparing a substantial yield of a tertiary hydroperoxide which comprises passing an oxygen-containing gas through an alkyl-substituted aromatic organic compound having the structural formula in liquid phase in the presence of a catalyst of the group consisting of heavy metal oxides, hydroxides, organic acid salts and mixtures thereof, the concentration of the catalyst in solution in the oxidation reaction mixture being from about 0.15 to about 0.8%, based on the alkylsubstituted aromatic compound, and in the structural formula R1 and R2 representing alkyl groups and Ar representing an alkaryl group containing two or more carbon atoms in the alkyl side chain.

2. The process of preparing a substantial yield of a tertiary hydroperoxide which comprises passing an oxygen-containing gas through an alkyl-substituted aromatic organic compound having the structural formula in liquid phase in the presence of a heavy metal salt of an organic acid, the concentration of the heavy metal salt in solution in the oxidation reaction mixture being from about 0.15 to about 0.8%, based on the alkyl-substituted aromatic compound, and in the structural formula R1 and R2 representing alkyl groups and Ar representing an alkaryl group containing two or more carbon atoms in the alkyl side chain.

3. The process of preparing a substantial yield of a tertiary hydroperoxide which comprises passing an oxygen-containing gas through an alkyl-substituted aromatic organic compound having the structural formula in liquid phase in the presence of a heavy metal salt or an organic acid, the concentration of the heavy metal salt in solution in the oxidation reaction mixture being from about 0.2 to about 0.6%, based on the alkyl-substituted aromatic compound, and in the structural formula R1 and R2 representing alkyl groups and Ar representing an alkaryl group containing two or more carbon atoms in the alkyl side chain.

4. The process of preparing a substantial yield of a tertiary hydroperoxide which comprises passing an oxygen-containing gas through an alkyl-substituted aromatic organic compound having the structural formula R2 Ar in liquid phase in the presence of a heavy metal salt of an organic acid, the concentration of the heavy metal salt in solution in the oxidation reaction mixture being from about 0.25 to about 0.5%, based on the alkyd-substituted aromatic compound, and in the structural formula R1 and R2 representing alkyl groups and Ar representing an alkaryl group containing two or more carbon atoms in the alkyl side chain.

5. The process of preparing a substantial yield of a tertiary hydroperoxide which comprises pass ing an oxygen-containing gas through an alkylsubstituted aromatic organic compound having the structural formula in liquid phase in the presence of a manganese salt of an organic acid, the concentration of the manganese salt in solution in the oxidation reaction mixture being from about 0.15 to about 0.8%, based on the alkyl-substituted aromatic compound, and in the structural formula R1 and R2 representing alkyl groups and Ar representing an alkaryl group containing two or more carbon atoms in the alkyl side chain.

0. The process of preparing a substantial yield of a tertiary hydroperoxide which comprises passing an oxygen-containing gas through an alkylsubstituted aromatic organic compound having the structural formula in liquid phase in the presence of manganese naphthenate, the concentration of the manganese naphthenate in solution in the oxidation reaction mixture being from about 0.15 to about 0.8%, based on the alkyl-substituted aromatic compound, and in the structural formula R1 and R2 representing alkyl groups and Ar representing an alkaryl group containing two or more carbon atoms in the alkyl side chain.

7. The process of preparing a substantial yield of a tertiary hydroperoxide which comprises passing oxygen through an alkyl-substituted aromatic organic compound having the structural formula o Rz Ar in liquid phase in the presence of a heavy metal salt of an organic acid, the concentration of the heavy metal salt in solution in the oxidation reaction mixture being from about 0.15 to about 0.8%, based on the alkyl-substituted aromatic compound, and in the structural formula R1 and R2 representing alkyl groups and Ar representing an alkaryl group containing two or more carbon atoms in the alkyl side chain.

8. The process of preparing a substantial yield of a,a-dimethyl-p-isopropylbenzy1 hydroperoxide which comprises passing an oxygen-containing gas through p-diisopropylbenzene in the liquid phase in the presence of a heavy metal salt of 10 an organic acid, the concentration of the heavy metal salt in solution in the oxidation reaction mixture being from about 0.15 to about 0.8%, based on the p-diisopropylbenzene.

9. The process of preparing a substantial yield of a,a-dimethyl-p-isopropylbenzyl hydroperoxide which comprises passing oxygen through p-diisopropylbenzene in the liquid phase in the presence of manganese naphthenate, the concentration of the manganese naphthenate in solution in the oxidation reaction mixture being from about 0.15 to about 0.8%, based on the p-diisopropylbenzene.

10. The process of preparing a substantial yield of 0.,a dimethyl-p-ethylbenzyl hydroperoxide which comprises passing an oxygen-containing gas through p-ethylisopropylbenzene in the liquid phase in the presence of a heavy metal salt of an organic acid, the concentration of the heavy metal salt in solution in the oxidation reaction mixture being from about 0.15 to about 0.8%, based on the p-ethylisopropylbenzene.

11. The process of preparing a substantial yield of (1,01. dimethyl-p-ethylbenzyl hydroperoxide which comprises passing oxygen through p-ethylisopropylbenzene in the liquid phase in the presence of cobalt linoleate, the concentration of the cobalt linoleate in solution in the oxidation reaction mixture being from about 0.15 to about 0.8%, based on the p-ethylisopropylbenzene.

12. The process of preparing a substantial yield of a,a,a,a-tetrarnethyl-p-Xylylene dihydroperox-.

ide which comprises passing an 0xygen-containing gas through p-diisopropylbenzene in the liquid phase in the presence of a heavy metal salt of an organic acid, the concentration of the heavy metal salt in solution in the oxidation reaction mixture being from about 0.15 to about 0.8% based on the p-diisopropylbenzene.

13. The process of preparing a substantial yield of p-butylisopropylbenzene hydroperoxide which comprises passing an oxygen-containing gas through p-butvlisopropylbenzene in the liquid phase in the presence of a heavy metal salt of an organic acid, the concentration of the heavy metal sa t in solution in the oxidation reaction mixture being from about 0.15 to about 0.8% based on the p-b-utyli opropylbenzene.

14. The process of preparing a substantial yield of triisopropylbenzene trihydroperoxide which comprises passing an oxygen-containing gas through triisopropylbenzene in the liquid phase in the presence of a heavy metal salt of an organic acid, the concentration of the heavy metal salt in the solution in the oxidation reaction mixture being from about 0.15 to about 0.8%, based on the triisopropylbenzene.

EUGENE J. LORAND. JOHN E. REESE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,302,466 Palmer et a1. Nov. 17, 1942 2,403,771 Vaughn et al July 9, 1946 2,430.864 Farkas et al Nov. 18, 1947 2,434,888 Rust et a1 Jan. 20, 1948 FOREIGN PATENTS Number Country Date 99,523 Switzerland June 1, 1923 784,016 France Apr. 15, 1935 OTHER REFERENCES Hock et al., Bern, vol. 7'7, pages 257 to 264 (1944). 

1. THE PROCESS OF PREPARING A SUBSTANTIAL YIELD OF A TERTIARY HYDROPEROXIDE WHICH COMPRISES PASSING AN OXYGEN-CONTAINING GAS THROUGH AN ALKYL-SUBSTITUTED AROMATIC ORGANIC COMPOUND HAVING THE STRUCTURAL FORMULA 